Personne :
Bergeron, François

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Structures organisationnelles
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Université Laval. Département de réadaptation
Identifiant Canadiana

Résultats de recherche

Voici les éléments 1 - 3 sur 3
  • Publication
    Mechanical loading modulates the differentiation state of vascular smooth muscle cells
    (Mary Ann Liebert, 2006-11-24) Bergeron, François; Grenier, Guillaume.; Germain, Lucie; Labbé, Raymond; Auger, François A.; Guignard, Rina; Baker, Kathleen; Rémy-Zolghadri, Murielle
    The cause underlying the onset of stenosis after vascular reconstruction is not well understood. In the present study, we evaluated the effect of mechanical unloading on the differentiation state of human vascular smooth muscle cells (hVSMCs) using a tissue-engineered vascular media (TEVM). hVSMCs cultured in a mechanically loaded three-dimensional environment, known as a living tissue sheet, had a higher differentiated state than cells grown on plastic. When the living tissue sheet was detached from its support, the release of the residual stress resulted in a mechanical unloading and cells within the extracellular matrix (ECM) dedifferentiated as shown by downregulation of differentiation markers. The relaxed living tissue sheet can be rolled onto a tubular mandrel to form a TEVM. The rolling procedure resulted in the reintroduction of a mechanical load leading to a cohesive compacted tissue. During this period, cells gradually redifferentiated and aligned circumferentially to the tubular support. Our results suggest that differentiation of hVSMCs can be driven by mechanical loading and may occur simultaneously in the absence of other cell types. The extrapolation of our results to the clinical context suggests the hypothesis that hVSMCs may adopt a proliferative phenotype resulting from the mechanical unloading of explanted blood vessels during vascular reconstruction. Therefore, we propose that this mechanical unloading may play an important role in the onset of vascular graft stenosis.
  • Publication
    Tissue reorganization in response to mechanical load increases functionality
    (2005-02-28) Bergeron, François; Langelier, Ève.; Grenier, Guillaume.; Germain, Lucie; Larouche, Danielle; Dupuis, Daniel; Rancourt, Denis; Auger, François A.; Gauvin, Robert; Baker, Kathleen; Rémy-Zolghadri, Murielle
    In the rapidly growing field of tissue engineering, the functional properties of tissue substitutes are recognized as being of the utmost importance. The present study was designed to evaluate the effects of static mechanical forces on the functionality of the produced tissue constructs. Living tissue sheets reconstructed by the self-assembly approach from human cells, without the addition of synthetic material or extracellular matrix (ECM), were subjected to mechanical load to induce cell and ECM alignment. In addition, the effects of alignment on the function of substitutes reconstructed from these living tissue sheets were evaluated. Our results show that tissue constructs made from living tissue sheets, in which fibroblasts and ECM were aligned, presented higher mechanical resistance. This was assessed by the modulus of elasticity and ultimate strength as compared with tissue constructs in which components were randomly oriented. Moreover, tissue-engineered vascular media made from a prealigned living tissue sheet, produced with smooth muscle cells, possessed greater contractile capacity compared with those produced from living tissue sheets that were not prealigned. These results show that the mechanical force generated by cells during tissue organization is an asset for tissue component alignment. Therefore, this work demonstrates a means to improve the functionality (mechanical and vasocontractile properties) of tissues reconstructed by tissue engineering by taking advantage of the biomechanical forces generated by cells under static strain.
  • Publication
    Isolation and culture of the three vascular cell types from a small vein biopsy sample
    (Tissue Culture Association, 2003-04-18) Grenier, Guillaume.; Germain, Lucie; Labbé, Raymond; Auger, François A.; Guignard, Rina; Rémy-Zolghadri, Murielle; Bergeron, François
    The availability of small-diameter blood vessels remains a significant problem in vascular reconstruction. In small-diameter blood vessels, synthetic grafts resulted in low patency; the addition of endothelial cells (EC) has clearly improved this parameter, thereby proving the important contribution of the cellular component to the functionality of any construct. Because the optimal source of cells should be autologous, the adaptation of existing methods for the isolation of all the vascular cell types present in a single and small biopsy sample, thus reducing patient’s morbidity, is a first step toward future clinical applications of any newly developed tissue-engineered blood vessel. This study describes such a cell-harvesting procedure from vein biopsy samples of canine and human origin. For this purpose, we combined preexisting mechanical methods for the isolation of the three vascular cell types: EC by scraping of the endothelium using a scalpel blade, vascular smooth muscle cells (VSMC), and perivascular fibroblasts according to the explant method. Once in culture, cells rapidly grew with the high level of enrichment. The morphological, phenotypical, and functional expected criteria were maintained: EC formed cobblestone colonies, expressed the von Willebrand factor, and incorporated acetylated low-density lipoprotein (LDL); VSMC were elongated and contracted when challenged by vasoactive agents; perivascular fibroblasts formed a mechanically resistant structure. Thus, we demonstrated that an appropriate combination of preexisting harvesting methods is suitable to isolate simultaneously the vascular cell types present in a single biopsy sample. Their functional characteristics indicated that they were suitable for the cellularization of synthetic prosthesis or the reconstruction of functional multicellular autologous organs by tissue engineering.